Wide dispersion + high efficiency + detail + coherence in a speaker?

I should say coherency is in fact about the entire presentation,   timbre, soundstage imaging, the whole shebang.   OHM Walshs exceed at all that but as I described not in exactly the same way say as a good pair of monitors in terms of "pinpoint" imaging.   More coherent overall than mbl  but hard to match mbl in terms of sound stage depth and associated 3-D imaging possible there.

ATC Active 40 or 50.  Active means efficiency isn't a factor.  Lots of detail, coherence, dispersion.  The pro 50 is better but the home 40 may be voiced for home use and sound better at low volumes. 

As the OP goes:

...
Vandersteens have a tiny sweetspot
MBL are lifeless and are not coherent at all.
Ohms lack in dynamics and detail.

A rather unambiguous way of stressing the importance of efficiency (i.e.: liveliness and dynamics), as well as implicitly downplaying soundstaging/imaging (or aspects of it) compared to other traits - certainly if Vandersteen and MBL are anything to go by in this regard. Single-driver speakers are also mentioned by the OP, and so may point to a desired carrier of coherency here other than liveliness (coherency likely means different things to different people). Options may not be multiple, and some compromises are inevitably to be made. Nevertheless, should be a fun journey.

JBL 4319 monitors. Mine are still breaking in and are still amazing me. Not highly effecient (92db) but 6 ohm and they don’t have to be aimed directly at me to sound wonderful.

The highs can reproduce bells and chimes like they are in the room and have bass that can rattle my windows.

As for coherence and the ability to unravel the music, they can undo Gordian’s knot without slicing it in two.

All the best,
Nonoise